The present invention relates to water closets, more particularly to an improved flush device for water closets which can be lifted to different levels via the robes and pulley to provide a multi-staged flush means for controlling the amount of flush water discharged.
Similar devices known from the prior art employ a ball cock and float ball; when water reaches a certain level, the float ball then closes a fill valve in the ball cock via the float rod. A flush valve is controlled by a flush lever connected to a flapper ball which automatically closes the flush valve upon the receding of the water level.
The disadvantage of such flush device of the prior art lies in its lack of flexibility to adjust the amount of discharge of flush water, such that every time when this flush device is activated, a tankful of water is discharged regardless of whether such large amount of flush water is needed. Since there are many occasions when smaller amount of flush water is sufficient, a two-staged flush system to save water is also known from the prior art.
As shown in FIG. 1, a prior art two-staged flush system has a duplicate set of flush devices including another flush valve installed at mid-tank level apparently requiring an additional flush rod, lift chain and handle. To install another handle, this design of the prior art also requires drilling another hole in the wall of the water tank, which is a difficult task to accomplish because the water tank is usually made of ceramic materials and easily broken.
Further, the water tank may not be big enough to accommodate two sets of flush device. Alternatively, a new water tank prefabricated to fit an additional set of flush devices would be uneconomical.